To meet a requirement of IMT-Advanced (International Mobile Telecommunication-Advanced), a next generation radio communications technology of ITU (International Telegraph Union, International Telecommunications Union), 3GPP launches LTE-Advanced, which is an enhanced and evolved version of LTE (Long Term Evolution, Long Term Evolution) that will be finalized soon, in order to meet technical specifications defined by ITU. LTE-Advanced introduces a relay node (Relay Node, RN) to implement functions such as radio network coverage with a high data rate, increasing cell edge throughput and providing new area coverage.
The relay node is connected to an evolved NodeB (eNB) through a radio link. Therefore, a terminal may first be connected to the relay node and then the relay node is connected to the evolved NodeB to realize an air interface of the terminal.
As shown in FIG. 1, after a relay node is introduced, user data is sent from a core network to an evolved NodeB (donor eNB) attached by the relay node, and sent by the evolved NodeB to the relay node, and finally the relay node sends the user data to a user equipment (User Equipment, UE).
For a user equipment that is initially served by the relay node, when the network side instructs the user equipment to hand over to the donor evolved NodeB, according to a handover procedure in a current LTE technology, the relay node may forward downlink data that is cached but not yet sent to the user equipment to the donor evolved NodeB. But the downlink data on the relay node is originally sent by the donor evolved NodeB to the relay node. Therefore, the same data is sent by the donor evolved NodeB to the relay node and then forwarded by the relay node back to the donor evolved NodeB. This causes a waste of a radio link between the relay node and the donor evolved NodeB.